Many communication systems use orthogonal frequency division multiplexed (OFDM) communication techniques. OFDM communication involves dividing a frequency bandwidth of a signal into frequency divisions or subcarriers, and the subcarriers are modulated with data for transmission from a transmitter to a receiver in a communication channel. The communication channel is, for example, an over-the-air channel, an optical fiber or a coax cable. Some of the subcarriers are also allocated to transmit a priori known values to enable channel estimation at the receiver. The subcarriers that carry known values are known as pilot subcarriers.